Re: [PATCH] ceph: show max caps in debugfs caps file

Jeff Layton
2020-05-21T11:09:59Z

On Thu, 2020-05-21 at 17:38 +0800, Yanhu Cao wrote:
> before
> ------
> total 1026
> avail 1024
> used 2
> reserved 0
> min 1024
>
> after
> ------
> total 1026
> avail 1024
> used 2
> max 2048
> reserved 0
> min 1024
>
> Signed-off-by: Yanhu Cao <gmayyyha@gmail.com>
> ---
> fs/ceph/caps.c | 6 ++++--
> fs/ceph/debugfs.c | 7 ++++---
> fs/ceph/super.h | 2 +-
> 3 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 5f3aa4d607de..e2c759a2ef35 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -404,8 +404,8 @@ void ceph_put_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap)
> }
>
> void ceph_reservation_status(struct ceph_fs_client *fsc,
> - int *total, int *avail, int *used, int *reserved,
> - int *min)
> + int *total, int *avail, int *used, int *max,
> + int *reserved, int *min)
> {
> struct ceph_mds_client *mdsc = fsc->mdsc;
>
> @@ -417,6 +417,8 @@ void ceph_reservation_status(struct ceph_fs_client *fsc,
> *avail = mdsc->caps_avail_count;
> if (used)
> *used = mdsc->caps_use_count;
> + if (max)
> + *max = mdsc->caps_use_max;

Can you lay out what value this will provide? I'm not convinced that
this information is really that helpful:

mdsc->caps_use_max is just set to the value of the "caps_max" mount
option, and that information is displayed in /proc/mounts if it's not
set to the default.

What might be more interesting is to track the most recent "max_caps"
value sent by the MDS (see the CEPH_SESSION_RECALL_STATE message
handling). Tracking that would give us a more dynamic view of the
current maximum requested by the MDS, which is often going to be less
than what "caps_max" was set to at mount time.

> if (reserved)
> *reserved = mdsc->caps_reserve_count;
> if (min)
> diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
> index 481ac97b4d25..942004376588 100644
> --- a/fs/ceph/debugfs.c
> +++ b/fs/ceph/debugfs.c
> @@ -138,16 +138,17 @@ static int caps_show(struct seq_file *s, void *p)
> {
> struct ceph_fs_client *fsc = s->private;
> struct ceph_mds_client *mdsc = fsc->mdsc;
> - int total, avail, used, reserved, min, i;
> + int total, avail, used, max, reserved, min, i;
> struct cap_wait *cw;
>
> - ceph_reservation_status(fsc, &total, &avail, &used, &reserved, &min);
> + ceph_reservation_status(fsc, &total, &avail, &used, &max,
> + &reserved, &min);
> seq_printf(s, "total\t\t%d\n"
> "avail\t\t%d\n"
> "used\t\t%d\n"
> "reserved\t%d\n"
> "min\t\t%d\n\n",
> - total, avail, used, reserved, min);
> + total, avail, used, max, reserved, min);
> seq_printf(s, "ino issued implemented\n");
> seq_printf(s, "-----------------------------------------------\n");
>
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 60aac3aee055..79aa42d9336c 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -700,7 +700,7 @@ extern void ceph_unreserve_caps(struct ceph_mds_client *mdsc,
> struct ceph_cap_reservation *ctx);
> extern void ceph_reservation_status(struct ceph_fs_client *client,
> int *total, int *avail, int *used,
> - int *reserved, int *min);
> + int *max, int *reserved, int *min);
>
>
>

--
Jeff Layton <jlayton@kernel.org>